1. Field of the Invention
This invention relates to tamper evident containers, and more particularly to closures having visible seals which reveal whether tampering or leakage has occurred, without the necessity of removing the closure to inspect the seal.
2. Description of Related Art
Containers such as jars with screw-on caps have been provided with various means for indicating tampering.
For example, my prior U.S. Pat. No. 4,778,069 discloses and claims a container having a tab extending from an inner seal through a slot in the container cover. Damage to the tab is indicative of tampering.
Patent No. 4,553,678 has a film or foil seal which is visible through a transparent screw cap.
Relative movement between an outer container cap and an inner liner is shown by indicia on the liner which can be seen through a window provided in the cap of patent No. 4,446,979.
In the package of U.S. Pat. No. 4,489,841, a color change in the skirt of a cap indicates that the package has been opened.
Patent No. 4,674,642 relates to a closure for a container having contents under vacuum. An inner liner has a projection which extends through an aperture in the container cap when vacuum is lost. However, if the container contents were an oil-based product such as peanut butter or mayonnaise, vacuum would be re-established after opening and re-closing of the container because of reaction of the contents with air admitted by opening of the container.